They have published a lot of information on their blog[1]. It's piecemeal, and around other articles about optimisations or security fixes or failures/postmortems, but it's there. Stuff like:

https://blog.cloudflare.com/how-we-use-hashicorp-nomad/

https://blog.cloudflare.com/cloudflare-deployment-in-guam/

https://blog.cloudflare.com/behind-the-scenes-with-stream-li...

1 - https://blog.cloudflare.com/